A fifth man has been arrested in connection with the assassination of Pakistan's former Prime Minister Benazir Bhutto, police have said.
The latest arrest comes three days ahead of parliamentary elections
Investigators described the suspect, Abdul Rasheed, as a key member of the gang that plotted the 27 December attack in which 20 other people died.
Four suspected Islamic militants have already been arrested in the case.
The latest arrest comes three days ahead of elections which were postponed after Ms Bhutto's murder.
On Wednesday, two of the arrested men, cousins Rufukat and Husnan Gul, confessed to helping Bhutto's attacker, the head of the investigation said.
In what he described as a "major breakthrough", Deputy Inspector General Abdul Majid said the two men had confessed to giving a bomb vest and a pistol to the suicide bomber identified as Bilal.
Last week, UK detectives said Ms Bhutto died from the effect of the bomb blast.
Two other suspects, including a 15-year-old boy, have also been arrested in connection with the killing.
The Pakistani government has blamed Taleban rebel leader Baitullah Mehsud, who is based in the troubled region of South Waziristan, for masterminding the assassination of Ms Bhutto. He has denied any involvement.